If you're new to Perl, which programming language are you proficient in? What resource are you using to aid your learning of Perl? And what have you tried so far?

If you're new to Perl, but competent in some other language, sometimes it helps for us to be aware of that so that we know how to answer in a way that will make the most sense in consideration of your background. If your background is that you don't know the first thing about programming, that would be helpful for us to know as well. Everyone starts somewhere, and there's no shame in that. We're also fairly familiar with many of the learning resources commonly available on the subject. So if we know where you're coming from in that regard as well, we may be able to sort of fill in the gaps or refer you to portions of that resource that might provide additional information. But like I said, everyone starts somewhere, and we all learned Perl somewhere along the way. There's nothing wrong with that.

Not everyone duplicate-posts their original question, and then one-ups that by duplicate-posting their followups as well. Some do though, so you're not alone. But in the absence of additional background information, that sort of thing will probably skew our assessment as to what level of computer literacy our answers should target.

One easy way to read from a flat file is to use the open function (described in better detail perlintro, open, and perlopentut). Next one would use the <> (diamond operator), as described in perlintro and perlop. This combined with a while(){} loop (perlintro and perlsyn) is almost all that's needed for the common idiom:

open my $file_handle, '<', 'filename.txt' or die $!;
while( <$file_handle> ) {
chomp;
# do something with the line held in $_
}
close $file_handle;